1. Field of the Invention
The present invention relates to a power semiconductor device module, and particularly relates to a power semiconductor device module for use in a power converter that controls electric equipment such as a motor.
2. Description of the Background Art
In a conventional power semiconductor device module, especially in a power semiconductor device module for use in applications required to have high reliability, such as a power semiconductor device module for use in railways, for example, as disclosed in Japanese Patent Application Laid-Open No. 2006-344841, a configuration has been adopted in which an insulating substrate with an electrode layer provided on each surface thereof is bonded by soldering onto a base plate made of copper or the like, and a semiconductor chip such as an IGBT (Insulated Gate Bipolar Transistor) or a free wheel diode is joined by soldering onto the insulating substrate.
In the power semiconductor device module with such a configuration, any of the base plate, the insulating substrate, the electrode layer on the insulating substrate, and a solder thickness is set to a uniform thickness, and the module is configured to make thermal resistance equal.
Recently, as a semiconductor substrate in place of a silicon substrate, there has been developed a semiconductor device by means of a semiconductor substrate having a wide band gap such as a semiconductor substrate formed of a silicon carbide (SiC)-based material, a gallium nitride-based material, or a diamond.
For example, a silicon carbide semiconductor device can be operated with a current density thereof increased from that of the conventional silicon semiconductor device. However, there has been a problem in that, when a semiconductor chip (SiC semiconductor chip) made up of the silicon carbide silicon device is mounted in a package with a conventional structure, a temperature rise due to heat generation of the semiconductor chip cannot be suppressed unless a configuration is adopted in which the thermal resistance is decreased in accordance with an increase in current density, thus shortening a product life.